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Growing Rhubarb in
Montana
by Robert Gough, Ph.D., Professor of Horticulture; and Jack Riesselman,
Ph.D., Professor Emeritus, Plant Sciences and Plant Pathology
MontGuide
Rhubarb is a hardy perennial that tolerates Montana’s cold winters and dry
climate and is a good source of vitamin C and iron. This fact sheet includes
tips on soil preparation, mulching, suitable cultivars, planting, harvesting, and
dividing crowns, as well as information about some common rhubarb pests.
MT200006AG Reviewed 3/10
GROWING VEGETABLES IN MONTANA IS TOUGH,
unless you grow rhubarb. This hardy perennial tolerates
Montana’s cold winters and dry climate, and is a good
source of vitamin C and iron. It is widely used in desserts,
jams and pies.
The genus name for rhubarb, Rheum, is derived from
Rha, the ancient name for the Volga River, where it grew
on the riverbanks. The Chinese cultivated rhubarb for
medicine as long ago as 2700 B.C. Marco Polo brought
the medicinal plant into Europe and it was
commonly grown in Italy by 1608.
But it wasn’t until 1778 that
it was actually used as a food
in tarts and pies. The plant
was brought to America
about 1790 and was being
marketed by 1822.
There are many cultivars
of rhubarb. The most
common are:
‘Canada Red’ This high
quality cultivar has small,
thick, tender petioles and is
very popular in Canada.
‘Cherry Red’ This vigorous red cultivar
produces long, thick deep-red petioles.
‘Crimson Red’ Also known as ‘Crimson Cherry,’
this cultivar forms brightly-colored red stalks with
the unique characteristic of being red throughout,
under normal localized growing conditions of the
Pacific Northwest.
‘Macdonald’ This cultivar produces pink stalks and is
vigorous and upright-growing. It is resistant to wilt
and root rot and is probably the most widely available
cultivar.
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‘Valentine’ This old cultivar produces long, thick, deepred petioles that retain their color when cooked. It is an
excellent choice for home gardens.
Growing Rhubarb
Rhubarb does best on slightly acid soils with a pH
between 6.0 and 6.8, but it will tolerate the somewhat
more alkaline Montana soils. It will grow in almost any
type of soil but is highly productive on fertile, welldrained soils high in organic matter.
Plant rhubarb roots
in spring as early as
the ground can be
worked. To prepare
the planting bed, dig
holes two feet deep
and two feet wide and
space them three feet
apart in all directions.
Fill the bottom of each
hole with a six inch layer of
compost or well-rotted manure.
Mix top soil that was dug
out of each hole with equal
amounts of compost or manure
and fill the hole with this
mixture to a depth of one foot.
Place the root piece in each hole
so that the top, where the plant
buds are located, sits 3-4 inches
below the soil surface.
Tamp the soil firmly around the roots and fill each hole
with the soil mixture until level with the surrounding soil.
If your soil remains too wet to work in early spring you can
plant rhubarb in the fall after the leaves have died down.
If you cannot depend upon winter snow cover, mulch the
fall-set crowns to reduce winter heaving.
Use no fertilizer in the planting year. Beginning in the
second year, side dress each plant with a half pound of a
complete fertilizer such as 16-16-16 just as the petioles
first appear. Continue this practice each spring and in fall
when the leaves have died down but before the ground
has frozen. Straw around the plants will keep weeds under
control.
The plants may begin to form flower stalks in
midsummer as a result of warm, long days. Remove these
flower stalks as soon as they appear. Letting them fully
form will shunt nutrients away from the petioles and
roots and into the unwanted seed heads.
Harvest no crop the year of planting. The plant uses
food from the leaves to nourish the roots and enlarge the
crown. If plants are healthy, harvest for a few weeks in the
second year by pulling the petioles from the crowns. Do
not cut them.
Never harvest all the petioles since doing so may
deplete the plant of sufficient nutrients to overwinter
the roots . Harvest period should last about 4-6 weeks in
subsequent years so long as plants remain vigorous.
The leaf blades of the rhubarb contain poisonous oxalic
acid in quantities sufficient to cause human fatalities if
they are ingested. DO NOT EAT RHUBARB LEAF
BLADES. Instead, cut the blades from the petioles (leaf
stalks) and eat only the stalks.
Propagation
D
After four to six years, rhubarb plants can become
crowded and the stalks will grow noticeably thinner.
Divide the crowns in the early spring before new shoots
emerge or in the fall after the foliage has died down.
Dig the crowns and cut them into sections between
the large buds. Leave at least one bud on each crown
section. Crown pieces should be as large as possible.
Protect the new crowns from drying or freezing if they
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are not to be planted immediately. Before replanting,
discard crown pieces that are damaged or rotted. Plant
the new crowns in the manner described above.
Pests
Rhubarb is a hardy perennial that is not usually seriously
affected by insect pests or diseases. There are a few,
however, of which you should be aware.
Several diseases can attack rhubarb but none are more
destructive than “Red Leaf.” In Canada, this bacterial
root and crown rot has destroyed up to 50 percent of
some plantings. In Montana, isolated outbreaks are
common and have caused individual patches to decline
rapidly. Examination of the crown and root area often
reveals a chocolate brown discoloration accompanied by
root cavities. However, the most visible symptom is the
development of red leaves on infected plants.
The pathogen, a bacterium called Erwinia rhapontici,
is readily transmitted via transplanting infected crowns.
In establishing new plantings only disease-free crowns
should be selected. Documented movement in Montana
has occurred when infected crowns are used to establish
new plantings. New crowns must not be replanted in
areas where the disease has previously been observed.
Evidence exists that root and foliage feeding insects can
move the bacteria from infected to uninfected plants.
Therefore, good insect management will also reduce
localized spread.
Several foliar diseases including both powdery and
downy mildew, gray mold, and various fungal leaf
spots are know to occur on rhubarb. However, due
to Montana’s general dry climate they are of little
or no importance, with the exception of a few wet
intermountain regions.
Virus diseases also attack rhubarb. While not common
in Montana, an occasional infection has been observed.
Turnip mosaic, a common virus in rhubarb, can be
mistaken for red leaf caused by Erwinia . Its presence has
not been verified in Montana but reports of this virus in
Canada are common.
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File under: Yard and Garden (Fruits)
Reviewed March 2010 200-310SA